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| #include <linux/module.h>
#include <linux/sched.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
// global var
static char *str = NULL;
// linux/seq_file.h
// void * (*start) (struct seq_file *m, loff_t *pos);
// void (*stop) (struct seq_file *m, void *v);
// void * (*next) (struct seq_file *m, void *v, loff_t *pos);
// int (*show) (struct seq_file *m, void *v);
/**
* author: aran
* fuction: seq_operations -> start
*/
static void *my_seq_start(struct seq_file *m, loff_t *pos)
{
if (0 == *pos)
{
++*pos;
return (void *)1; // return anything but NULL, just for test
}
return NULL;
}
/**
* author: aran
* fuction: seq_operations -> next
*/
static void *my_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
// only once, so no next
return NULL;
}
/**
* author: aran
* fuction: seq_operations -> stop
*/
static void my_seq_stop(struct seq_file *m, void *v)
{
// clean sth.
// nothing to do
}
/**
* author: aran
* fuction: seq_operations -> show
*/
static int my_seq_show(struct seq_file *m, void *v)
{
seq_printf(m, "current kernel time is %llu\n", (unsigned long long) get_jiffies_64());
seq_printf(m, "str is %s\n", str);
return 0; //!! must be 0, or will show nothing T.T
}
// global var
static struct seq_operations my_seq_fops =
{
.start = my_seq_start,
.next = my_seq_next,
.stop = my_seq_stop,
.show = my_seq_show,
};
// file_operations
// int (*open) (struct inode *, struct file *)
// ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *)
/**
* author: aran
* fuction: file_operations -> open
*/
static int proc_seq_open(struct inode *inode, struct file *file)
{
return seq_open(file, &my_seq_fops);
}
/**
* author: aran
* fuction: file_operations -> write
*/
static ssize_t proc_seq_write(struct file *file, const char __user *buffer, size_t count, loff_t *f_pos)
{
//分配临时缓冲区
char *tmp = kzalloc((count+1), GFP_KERNEL);
if (!tmp)
return -ENOMEM;
//将用户态write的字符串拷贝到内核空间
//copy_to|from_user(to,from,cnt)
if (copy_from_user(tmp, buffer, count)) {
kfree(tmp);
return -EFAULT;
}
//将str的旧空间释放，然后将tmp赋值给str
kfree(str);
str = tmp;
return count;
}
// global var
static struct file_operations proc_seq_fops =
{
.owner = THIS_MODULE,
.open = proc_seq_open,
.read = seq_read,
.write = proc_seq_write,
.llseek = seq_lseek,
.release = seq_release,
};
static int __init my_init(void)
{
struct proc_dir_entry *file;
// create "/proc/proc_seq" file
file = proc_create_data(
"jif", // name
0666, // mode
NULL, // parent dir_entry
&proc_seq_fops, // file_operations
NULL // data
);
if (NULL == file)
{
printk("Count not create /proc/jif file!\n");
return -ENOMEM;
}
return 0;
}
static void __exit my_exit(void)
{
remove_proc_entry("jif", NULL);
kfree(str);
}
module_init(my_init);
module_exit(my_exit);
MODULE_AUTHOR("aran");
MODULE_LICENSE("GPL");
|
